Leak detecting devices serve for detecting leaks in test objects containing a test gas, such as helium. Leak detecting devices are known which comprise a hand-held sniffing tip. Gas is taken in through the sniffing probe and fed to a test gas sensor. The devices require a vacuum pump which is normally accommodated in a floor- or table-mounted device, i.e. a basic device placed on the floor or on a table. The basic device frequently also includes the test gas detector. Said test gas detector may be a mass spectrometer or a structurally smaller infrared gas analyzer.
Normally, the sniffing probe is connected with the basic device via a capillary line. The operator can relatively easily move the sniffing probe in the vicinity of the test object in search of possible leaks. However, such leak detecting devices have a longer response time. The response time is the period between the intake of the leakage gas and the indication. The response time is determined by the length of the sniffing line which is typically 5 meters. Added to this is the response time of the test gas detector.
WO 03/008923 A2 describes a sniffing-type leak detector where the test gas detector is integrated in a handpiece to which the sniffing probe is attached. The handpiece may be connected with the floor- or table-mounted basic device via a line, wherein the basic device comprises, inter alia, a vacuum pump and an indicator means. Said leak detecting device has a short response time due to the short distance between the intake opening of the sniffing probe on the one hand and the test gas detector on the other hand. However, the handpiece with the sensors arranged therein is large and heavy such that the use of the leak detecting device in continuous operation is fatiguing to the operator. Further, constricted regions of the test objects are difficult to access by the voluminous handpiece.